1. Field of the Invention
The present invention relates to keyboards and other devices which require manipulation via extension of the fingers, and in particular to a keyboard designed to minimize stress and injury related to carpal tunnel syndrome and other repetitive stress and strain injuries.
2. Description of Related Art
Incidents of Repetitive Strain Injuries (RSI), also known as Cumulative Trauma Disorder (CTD), such as Carpal Tunnel Syndrome (CTS) are increasing at an astronomical rate, affecting nearly two million workers annually and costing an estimated $20 billion per year in workers' compensation, medical benefits, and lost wages. RSI to the upper extremities results, in part, from the repetitive reaching, stretching, bending, flexing, and twisting of fingers. Maintaining the wrist in an awkward position during these repetitive motions increases the likelihood of injury. Holding the body and upper extremities in a static position (either sitting or standing) associated with keyboard use and data input also increases the likelihood of injury. Over time, these awkward repetitive motions can inflame soft tissue, creating pressure on various nerves and causing pain, numbness, and tingling sensations in the upper extremities. RSI may result in pain, numbness, weakness, or loss of dexterity or use of the hands and fingers.
Computer keyboard operators such as secretaries, data entry personnel, computer programmers, and journalists are among the most frequent victims of RSI. From the standpoint of typing speed, keyboards have advantageously evolved to the point where pauses in typing required by typewriters for carriage returns, paper feeds, and manual error corrections are no longer required While disadvantageous from an efficiency standpoint, these typing pauses provided breaks in the repetitive motions associated with typing. Consequently, the occurrence of repetitive strain injuries was much lower than it is today.
Despite the increased efficiency of the keyboard, the evolution of the keyboard from a health standpoint has been largely overlooked. With a conventional keyboard, the palms "float" in the air or rest on the desk or a conventional wrist rest located in front of and below the keyboard. With a conventional wrist rest, the wrist is forced to bend upwards to place the fingers on and depress the keys. Consequently, the muscle and tendons in the hands, arms, neck, and shoulders must continually support the fingers at this upward angle. Maintaining this position while typing for an extended period of time can strain the muscles and tendons of the hands, arms, neck, and shoulders and significantly contributes to repetitive strain injuries.
Additionally, many keyboards today have a non-linear relationship between the force applied to a key relative to the downward distance a key travels during a key stroke. That is, many keyboards require a relatively large force to initiate a key stroke, but require a relatively small force on the keyboard key for the remainder of the stroke. The result is that often a greater force than necessary is applied to a key during the latter portion of the key stroke, and the abrupt beginning and end of the stroke results in an impact or shock and vibration on the fingers. While this effect is relatively insignificant in striking a single key, the cumulative effect of these forces, vibrations, and shocks from continuous typing can aggravate nerves and soft tissue in the upper extremities to the point that CTS and other repetitive strain injuries can occur.
Commercially available keyboards that attempt to address some of these issues do so by changing the layout of the keys. These keyboards are intimidating and inhospitable to typists who are used to the traditional layout and have failed to gain popularity.
Moreover, conventional wrist rests are available that support the fingers and hands of the user above the keys of the keyboard. Such conventional wrist rests also may be attached to the keyboard or sloped away therefrom. Known wrist rests may be formed of soft or hard material.